A reproducible model for the laboratory cultivation of Neisseria gonorrhoeae has been developed which allows for the study of viable gonococci and human leukocyte interactions. Cultivation of gonococci in the allantoic cavity of ten-day chick embryos ensures the following critical properties necessary for subsequent in vitro study of these organisms: (1) stability of colonial type (virulent or type 1 and 2, avirulent or type 3 and 4); (2) log phase growth (one log increase over four hours of incubation on a reciprocating shaker); (3) absence of clumping and (4) resistance to killing by fresh normal human serum (10- 50%). Employing a modification of the Maaloe technique, log phase virulent gonococci resist phagocytosis by human polymorphonuclear leukocytes in the presence of 10% fresh human serum, 10% heat- inactivated human serum and in the absence of serum. To rule out that gonococci were not ingested and subsequently multiplied intracellularly, cell-associated organisms were incubated with 1 microgram/ml of Penicillin G after the 60 minute incubation period; greater than 99% of organisms were killed by penicillin demonstrating that surviving gonococci after 60 minutes of incubation with human leukocytes were in the extracellular population. Phagocytosis of stationary virulent gonococci does occur in the presence of 10% fresh human serum, 10% heat- inactivated serum and in the absence of serum. Phagocytosis of log phase avirulent gonococci occurs in the presence of 10% fresh human serum but not with heat-inactivated serum or in the absence of serum. The cell-associated counts parallel the total and extracellular counts suggesting that gonococci, once ingested by polymorphonuclear leukocytes are rapidly killed.